Interlayer-Engineered Local Epitaxial Templating Induced Enhancement in Polarization (2P_r > 70 μC/cm²) in Hf_0.5Zr_0.5O₂ Thin Films

In this work, we report a high remnant polarization, $2{P}_{r}>$ 70 $\mu \text{C}$ /cm ² in thermally processed atomic layer deposited Hf _0.5 Zr _0.5 O ₂ (HZO) film on Silicon with NH ₃ plasma exposed thin TiN interlayer (IL) and tungsten (W) as a top electrode. The effect of IL on the ferroelectric properties of HZO is compared with standard metal–ferroelectric–metal and metal–ferroelectric–semiconductor (MFS) structures. X-ray diffraction shows that the orthorhombic (o) phase increases as TiN is thinned. However, the strain in the o-phase is highest at 2 nm TiN and then relaxes significantly for the no-TiN case. High-resolution transmission electron microscopy (HRTEM) images reveal that the ultrathin TiN acts as a seed layer for the local epitaxy in HZO potentially increasing the strain to produce a $2\times $ improvement in the remnant polarization. Finally, the HZO devices are shown to be wake-up-free and exhibit endurance ${10}^{{6}}$ cycles. This study opens a pathway to achieve epitaxial ferroelectric HZO films on Si with improved memory performance.